JP7183685B2 - Composition for polyurethane integral skin foam, polyurethane integral skin foam, and method for producing the same - Google Patents

Description

The present invention relates to a composition for polyurethane integral skin foam (hereinafter sometimes referred to as "ISF"), ISF, and a method for producing the ISF.

ISF is widely used as a material for shoe soles and interior parts of automobiles such as steering wheels because of its good productivity, mechanical strength, and good feel, and is suitable for high-performance shoe soles. The technology of ISF, which has excellent mechanical strength while having an extremely high impact resilience, has not been known so far.

Patent Document 1 proposes a highly elastic flexible polyurethane foam having a relatively high density using diphenylmethane diisocyanate (hereinafter sometimes referred to as "MDI").

However, the polyurethane foam uses a cross-linking agent and increases the amount of chemical cross-linking to achieve a high elastic modulus. may not be obtained.

Further, Patent Document 2 describes a method of providing a low-density polyurethane molding as a shoe sole member, but the process is complicated, and the elastic modulus disclosed is not sufficient.

In addition, US Pat. No. 5,300,004 describes a method for providing high modulus polyurethane foams.

However, since the polyurethane foam uses a polymeric form of MDI or a modified form of carbodiimide, there is a possibility that high mechanical strength cannot be obtained. In addition, the isocyanate used is polytetramethylene ether glycol with high crystallinity, and the isocyanate group content is low, so it is highly viscous, and it is expected that it will be difficult to maintain a liquid state at room temperature, so care must be taken in handling. Become.

Japanese Patent Application Laid-Open No. 2003-342343 Japanese Patent Application Publication No. 2015-507513 JP 2017-105913 A

The present invention has been made in view of the above background art, and an object of the present invention is to provide an ISF having a high impact resilience and excellent mechanical strength and productivity, and to provide a method for producing the ISF. be.

As a result of intensive study and research, the present inventors have found that an organic poly having a specific isocyanate group content obtained from a specific MDI component and dipropylene glycol (hereinafter sometimes referred to as "DPG") By using an isocyanate composition, it was discovered that these problems could be solved, and the present invention was completed.

That is, the present invention includes the following embodiments (1) to (6).

(1) An ISF composition comprising an organic polyisocyanate composition (A), a polyol component (B), a catalyst (C), and a blowing agent (D), wherein the organic polyisocyanate composition (A) is MDI containing an isocyanate group-terminated prepolymer obtained from an isocyanate component containing DPG and 4,4'-MDI, 2,2'-MDI and 2,4'-MDI in the isocyanate component containing MDI The total content is 97% by mass or more, and the total content of 2,2′-MDI and 2,4′-MDI in MDI in the isocyanate component containing MDI is less than 3% by mass; A composition for ISF, characterized in that the organic polyisocyanate composition (A) has an isocyanate group content of 15 to 25% by mass.

(2) The above ( The composition for ISF according to 1).

(3) ISF obtained from the composition for ISF described in (1) or (2) above.

(4) The ISF according to (3) above, characterized in that the foam density is 200-400 kg/m ³ .

(5) The above (3) or (4), wherein the impact resilience is 50% or more, the tear strength is 100 N/cm or more, and the Split Tear Strength is 2.50 kg/cm or more. ISF as described in .

(6) A method for producing ISF obtained by reacting and foaming an organic polyisocyanate composition (A) and a polyol component (B) in the presence of a catalyst (C) and a blowing agent (D). The organic polyisocyanate composition (A) contains an isocyanate group-terminated prepolymer obtained from an isocyanate component containing MDI and DPG, and 4,4'-MDI and 2 in the isocyanate component containing MDI. The total content of ,2'-MDI and 2,4'-MDI is 97% by mass or more, and 2,2'-MDI and 2,4'-MDI account for MDI in the isocyanate component containing MDI. A method for producing ISF, characterized in that the total content is less than 3% by mass and the isocyanate group content of the organic polyisocyanate composition (A) is 15 to 25% by mass.

ADVANTAGE OF THE INVENTION According to this invention, mechanical strength can be improved notably, while having high impact resilience in ISF. In addition, the ISF obtained by the present invention is very useful as it can be widely used for materials that require high elasticity, such as shoe sole resins. In addition, high production stability can be achieved with common foaming equipment during ISF production.

The present invention will now be described in more detail.

The composition for ISF of the present invention comprises an organic polyisocyanate composition (A), a polyol component (B), a catalyst (C), and a blowing agent (D), wherein the organic polyisocyanate composition (A) contains an isocyanate-terminated prepolymer of MDI and DPG.

The isocyanate component containing MDI used for obtaining this isocyanate group-terminated prepolymer has MDI (including 4,4'-MDI, 2,2'-MDI and 2,4'-MDI) in the isocyanate component. and the total content of 2,2'-MDI and 2,4'-MDI in the MDI (hereinafter also referred to as MDI isomer content) is less than 3% by mass. and

The MDI content in the isocyanate component containing MDI in the present invention is 97% by mass or more, preferably 98% by mass or more. When the MDI content is less than 97% by mass, the mechanical strength of the ISF is lowered due to an increase in the number of isocyanate functional groups.

Moreover, the MDI isomer content ratio in MDI is less than 3% by mass, preferably less than 2% by mass. When the MDI isomer content ratio is 3% by mass or more, the mechanical strength of the ISF is reduced due to the deterioration of the crystallinity of the MDI portion.

The isocyanate group content of the organic polyisocyanate composition (A) used in the present invention is 15 to 25% by mass, preferably 16 to 24% by mass. When the isocyanate group content is less than 15% by mass, the viscosity of the organic polyisocyanate becomes very high, making it difficult to introduce it into a foaming device, and the mixing capacity of an ordinary foaming device for isocyanates and polyols is sufficiently uniform. not mixed into On the other hand, when the isocyanate group content is 25% by mass or more, the reaction between isocyanate, polyol, and water as a blowing agent becomes random, and it is presumed that this is caused by the enlargement of the urea bond repeating unit caused by the reaction between isocyanate and water. A significant decrease in mechanical strength is observed.

The organic polyisocyanate composition (A) used in the present invention can use an isocyanate group-terminated prepolymer obtained from PTMEG in addition to an isocyanate group-terminated prepolymer obtained from an isocyanate component containing MDI and DPG. . PTMEG used for obtaining the organic polyisocyanate composition (A) has a number average molecular weight of 1,250 to 3,500, preferably 1,500 to 3,500. If the number average molecular weight is below the lower limit, the PTMEG chains will not function sufficiently as soft segments, making it difficult to achieve the target rebound resilience. On the other hand, if the molecular weight exceeds the upper limit, the hardness of the ISF suitable for shoe soles and the like cannot be obtained, and the crystallinity of the PTMEG chain increases, resulting in the problem that the viscosity of the organic polyisocyanate becomes too high.

PTMEG used for obtaining the organic polyisocyanate composition (A) is preferably obtained by ring-opening polymerization of tetrahydrofuran alone, and is preferably bifunctional. By using such PTMEG, it is possible to obtain good mechanical properties such as impact resilience, elongation, and tear strength, which is preferable.

Further, even if an ether unit other than tetrahydrofuran is introduced into the molecule up to 10 mol % as a raw material monomer component before polymerization of PTMEG, the effect of the present invention is not greatly impaired. In general, it is possible to introduce 1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, etc. for the purpose of liquefying PTMEG at room temperature.

In addition, the MDI used in the organic polyisocyanate composition (A) may contain polyphenylene polymethyl polyisocyanate (polymeric MDI, hereinafter also referred to as p-MDI) having a similar structure. Since there is a risk that the elongation rate of ISF will decrease and ISF coloring due to p-MDI will occur, the content of p-MDI should be 3% by mass or less based on the MDI used in the organic polyisocyanate composition (A). more preferably 2% by mass or less, and most preferably no p-MDI is used.

The organic polyisocyanate composition (A) contains the above-described urethane modified product, and MDI and MDI that is liquid at room temperature (hereinafter referred to as "liquid MDI") are used in combination, and this is mixed with DPG or PTMEG. An organic polyisocyanate composition containing a urethane-modified isocyanate group-terminated prepolymer can also be suitably used.

Examples of liquid MDI that can be used in the organic polyisocyanate composition (A) include those obtained by known methods.
(1) MDI is reacted at 200° C. or higher,
(2) Add trimethyl phosphate, triethyl phosphate, etc. to MDI as a catalyst and react at 170° C. or higher, or
(3) Add a phosphorene compound such as 3-methyl-1-phenyl-2-phosphorene-1-oxide to MDI as a catalyst, react at 70° C. or higher, and add a reaction terminator at a predetermined reaction rate. ,
It contains at least one selected from the group consisting of a partially carbodiimide-modified MDI and a partially uretonimine-modified MDI obtained by a method such as the above.

In addition, after the above reaction is completed and a reaction terminator is added, the obtained liquid MDI is stored at a temperature of 50° C. or lower for 24 hours or more, and gel permeate The total content of carbodiimide-modified MDI and uretonimine-modified MDI in liquid MDI measured by a method that does not decompose uretonimine bonds, such as chromatography, is preferably 5 to 40% by mass, more preferably 10 to 35% by mass. be. When the total content of carbodiimide-modified MDI and uretonimine-modified MDI is within the above range, a suitable number of isocyanate functional groups can be obtained, and the viscosity can be made suitable during use. Further, when ISF is used, the strength and impact resilience can be satisfied.

The total content of 2,2'-MDI and 2,4'-MDI in this liquid MDI before carbodiimide modification or uretonimine modification is preferably 60% by mass or less. If the isomer content exceeds 60% by mass, productivity may deteriorate due to decreased reactivity.

Furthermore, the liquid MDI that can be used for the organic polyisocyanate (A) can contain a small amount of p-MDI in the MDI before carbodiimide modification or uretonimine modification.

However, p-MDI has a higher average number of isocyanate functional groups than liquid MDI, and the MDI before carbodiimide modification or uretonimine modification should be kept to a maximum of 3% by mass, more preferably 2% by mass or less. , most preferably not included.

PTMEG (b1) in the present invention preferably has a number average molecular weight of 600 to 3,500, more preferably 1,000 to 3,500. The content of (b1) in the polyol component (B) is preferably 80% by mass or more, more preferably 90% by mass or more. Below the lower limit, the rebound resilience of the resulting ISF may not be sufficiently high, and mechanical properties such as tear strength may deteriorate.

A cross-linking agent (b2) having 2 to 4 functional groups can be used as the polyol component (B) used in the present invention. Specifically, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, tetramethylene ether glycol, cyclohexanediethanol, glycerin, pentaerythritol, trimethylolpropane, monoethanolamine, diethanolamine, triethanol. Amines, diisopropanolamine, triisopropanolamine, and the like can be used. Among these, amine-based alcohols having particularly high reactivity are preferred.

As the polyol component (B), another polyol (b3) can be added within a range that does not lower the rebound resilience. Other polyols include polypropylene ether polyols (abbreviated as PPG) generally used in urethane resins, polyester polyols, naturally derived polyols such as castor oil, polybutadiene polyols, and dimer acid ester polyols.

As the catalyst (C), various urethanization catalysts known in the art can be used. For example, triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N', N″N″-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl)ether, triethylenediamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, 1-butyl- Tertiary amines such as 2-methylimidazole and organic acid salts thereof, aminoalcohols such as dimethylethanolamine, N-trioxyethylene-N,N-dimethylamine, N,N-dimethyl-N-hexanolamine, and Organic metal compounds such as these organic acid salts, stannus octoate, dibutyltin dilaurate, dioctyltin dilaurate, zinc naphthenate, and the like are included. These catalysts can be used in combination of two or more if necessary. Further, these catalysts can be used by dissolving them in various solvents, polyols, plasticizers, etc. for reasons such as viscosity reduction, liquefaction, and volume increase for improving the weighing accuracy of molding machines.

Water is desirable as the blowing agent (D) used in the present invention, but if necessary, known agents that do not have a significant impact on the global environment can be used. These known blowing agents are of two types: inert low boiling point solvents and reactive blowing agents. The former includes dichloromethane, hydrofluorocarbons, hydrofluoroolefins, acetone, methyl formate, hexane, pentane, isopentane, cyclopentane, Furthermore, nitrogen gas, carbon dioxide gas, air, and the like can be mentioned. Examples of the latter include azo compounds and sodium bicarbonate, which are decomposed to generate gas at temperatures higher than room temperature.

A viscosity reducing agent may be used in the present invention to reduce the viscosity of the ISF composition. Viscosity reducing agents include liquid substances generally used to reduce the viscosity of high-viscosity liquids that do not contain active hydrogen groups, carbodiimide groups, formyl groups, etc. that react with isocyanate groups. Such materials have a viscosity of 100 mPa s or less at 25 ° C. from the viewpoint of viscosity reduction effect, a melting point of 0 ° C. or less from the viewpoint of handling, and a flash point of 70 measured by the method of JIS K2265 from the viewpoint of safety. °C or higher, toxicity, environmental pollution and the like are preferably low. Specific examples include diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dioctyl phthalate, diisononyl phthalate, diethyl adipate, dipropyl adipate, dibutyl adipate, dioctyl adipate, diisononyl adipate, and diethyl maleate. , dipropyl maleate, dibutyl maleate, dioctyl maleate, tricresyl phosphate, tris-β-chloropropyl phosphate, acetyl tributyl citrate, dibenzyl ether and the like.

The amount of the viscosity reducing agent to be added is preferably 15% by mass or less with respect to the total amount of the organic polyisocyanate composition (A), polyol component (B), catalyst (C) and blowing agent (D). If it exceeds 15% by mass, there is a risk that the moldability of the ISF molded product will deteriorate and mechanical properties such as impact resilience and tear strength will decrease. The viscosity reducing agent may be added in advance to the organic polyisocyanate composition (A) or the polyol component (B), or may be added separately during foam production.

In the present invention, auxiliary agents may be used as necessary. Examples of such auxiliary agents include foam stabilizers, pigments or dyes, mica, reinforcing materials or fillers such as glass fibers, flame retardants, antioxidants, ultraviolet absorbers, light stabilizers, antifungal agents, Antibacterial agents, VOC catchers and the like can be mentioned, and can be used as necessary.

Known foam stabilizers generally used in polyurethane foam production can be mentioned as foam stabilizers. Examples thereof include polydimethylsiloxane-polyalkylene oxide block polymer and vinylsilane-polyalkylene polyol polymer.

The ISF of the present invention can be obtained from the ISF composition described above. In the ISF, for example, the organic polyisocyanate composition (A) and the polyol component (B) are stirred and mixed in the presence of the catalyst (C), the foaming agent (D), and optionally an auxiliary agent, etc. It is produced as a molded foam obtained by injecting it into a mold, or as a continuous sheet-like foam obtained by injecting it into a conveyor having walls on the top, bottom, left, and right. In both production methods, the components other than the organic polyisocyanate composition (A) are mixed in advance to prepare a polyol premix, and the two components of this and the organic polyisocyanate composition (A) are mixed and foamed. Alternatively, a method is possible in which all components are separately introduced into the mixing head of a stirring mixer and foamed.

The molar ratio of all isocyanate groups in the organic polyisocyanate composition of the present invention to all isocyanate-reactive groups in the water-containing isocyanate-reactive compound (isocyanate group/NCO-reactive group) is 0.4 to 1.0. 2 (isocyanate index (NCO INDEX) = 40 to 120), more preferably 0.5 to 1.1 (NCO INDEX = 50 to 110).

The density of the ISF according to the present invention is preferably 200-400 kg/m ³ . In particular, considering economy and productivity, it is preferable to adjust to 350 kg/m ³ or less.

Although it depends on the type and amount of the catalyst (C), when only water is used as the blowing agent, the number of parts of water to be added to achieve this density range is It is preferably 0.3 to 3.0 parts by mass.

As described above, the ISF of the present invention is not particularly limited in its application, but has a rebound resilience of 50% or more, a tear strength of 100 N/cm or more, and a split tear strength of 2.50 kg/cm or more. As described above, because of its high rebound resilience and high mechanical strength, by replacing foamed resin and ISF used for conventional shoe soles, parts of shoe soles, shoe insoles, etc. with ISF according to the present invention, You can get very good usability, strength and durability.

Specific examples of the present invention will be described below, but the present invention is not limited only by these examples. In the examples, all parts and percentages are based on mass unless otherwise specified.

[Organic polyisocyanate composition Synthesis Example I-1]
A 1 L reactor equipped with a stirrer, thermometer, cooler, and nitrogen gas inlet tube was charged with 859 g of low isomer ratio MDI, heated to 75° C., charged with 141 g of DPG, and stirred while maintaining the temperature. The urethanization reaction was carried out for 3 hours while uniformly mixing at . After cooling to 40° C., an organic polyisocyanate composition “I-1” (MDI content ratio 100%, MDI isomer ratio 1%, NCO group content ratio 20.0%, viscosity 2330 mPa·s at 40° C.) was obtained.

[Organic polyisocyanate composition Synthesis Example I-2]
A 1 L reactor equipped with a stirrer, thermometer, cooler, and nitrogen gas inlet tube was charged with 773 g of low isomer ratio MDI, heated to 75° C., charged with 127 g of DPG, and stirred with a stirring blade while maintaining the temperature. The urethanization reaction was carried out for 3 hours while uniformly mixing at . Then, 100 g of DOM was charged, mixed uniformly with a stirring blade at 50° C. for 1 hour, and then cooled to 40° C. to obtain an organic polyisocyanate composition “I-2” (MDI content ratio 100%, MDI isomer ratio 1%, An NCO group content of 18.0% and a viscosity of 860 mPa·s at 40° C.) were obtained.

[Organic polyisocyanate composition Synthesis Example I-5]
577 g of low isomer ratio MDI and 115 g of liquid MDI were charged into a 1 L reactor equipped with a stirrer, thermometer, cooler, and nitrogen gas inlet tube, heated to 75° C., then 107 g of DPG was charged, and the temperature was adjusted to The urethanization reaction was carried out for 3 hours while uniformly mixing with a stirring blade while maintaining the temperature. After that, 200 g of DOM was charged, uniformly mixed with a stirring blade at 50° C. for 1 hour, and then cooled to 40° C. to obtain an organic polyisocyanate composition “I-5” (MDI content ratio of 95%, MDI isomer ratio of 1%, An NCO group content of 18.0% and a viscosity of 450 mPa·s at 40° C.) were obtained.

[Isocyanate Synthesis Examples I-3 to 4, I-6 to 11]
Organic polyisocyanate compositions I-3 to 4 and I-6 to 11 were obtained by performing the same operations as in I-1, I-2 and I-5 using the raw materials shown in Tables 1 and 2. . The raw material formulations in the table are shown in parts by mass.

[Preparation of polyol component]
Raw materials were uniformly mixed in the proportions shown in Table 3 to prepare polyol components P-1 and P-2 as polyol premixes. In addition, the raw material composition is shown in parts by mass.

The raw materials used in Tables 1 to 3 are as follows.
- Low isomer ratio MDI: MDI content ratio of 100%, MDI isomer ratio of 1%, NCO group content ratio of 33.5%.
- High isomer ratio MDI: MDI content ratio of 100%, MDI isomer ratio of 55%, NCO group content ratio of 33.5%.
・Liquid MDI: carbodiimide-modified and uretonimine-modified MDI with an MDI content of 70%, an MDI isomer ratio of 1%, and an NCO group content of 29.0%
・DPG: dipropylene glycol (manufactured by ADEKA)
・ DOM: bis(2-ethylhexyl) maleate (manufactured by Daihachi Chemical Industry Co., Ltd.)
・ PG: propylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ DEG: diethylene glycol (manufactured by Mitsubishi Chemical Corporation)
・ MPO: 2-methyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)
・PTG-3000SN: PTMEG, number average molecular weight = 3000 (trade name, manufactured by Hodogaya Chemical Industry Co., Ltd.)
・PTMEG2000: PTMEG, number average molecular weight = 2000 (trade name, manufactured by INVISTA)
・DABCO NCIM: 1-isobutyl-2-methylimidazole (trade name, manufactured by Evonik)
- SRX-280A: Silicone foam stabilizer (trade name, manufactured by Dow Corning Toray Co., Ltd.).

[Production of ISF]
ISFs were produced using isocyanate group-terminated prepolymers I-1 to I-11 and polyol premixes P-1 to P-2 as organic polyisocyanate compositions.

That is, each organic polyisocyanate composition adjusted to a temperature of 40° C. and a polyol premix at the ratio shown in Tables 4 and 5 were heated at 7000 rpm. p. m. It was mixed and stirred with a desktop mixer at a rotation speed of . After heating to 60° C. and applying a release agent, this mixture was poured into a dry metal mold of 200 mm×200 mm×10 mm, and then cured for 7 minutes with a lid. After curing, it was taken out from the mold to obtain an ISF test piece (hereinafter abbreviated as TP). The resulting TP was heat-cured at 70° C. for 24 hours, and then evaluated for density, hardness, mechanical properties, and the like.

<Physical property measurement>
- Density: Measured according to JIS K7222.
- Hardness (Asker C, surface hardness with skin): Measured according to JIS K7312.
- Impact resilience: Measured according to JIS K6400-3.
- TR (tear strength, using B-type dumbbell): Measured according to JIS K6400-5.
・Split Tear Strength was measured according to ISO20875.

<Comprehensive evaluation>
Those exceeding the standard values in all of the following three physical property items were judged to be good.
- Impact resilience: 50% or more - TR: 100 N/cm or more - Split Tear Strength: 2.50 kg/cm or more.

Tables 4 and 5 show the evaluation results of the produced ISF.

As is clear from Tables 4 and 5, the ISF obtained from the isocyanate liquid at room temperature of the present invention has a high impact resilience and excellent mechanical strength.

The polyurethane integral skin foam according to the present invention, which has a high impact resilience and excellent mechanical properties not found in the conventional market, can be used for shoe soles, shoe insoles, parts of industrial machinery, toys, musical instruments, etc. It brings about excellent effects such as weight reduction.

Claims (5)

An integral skin foam composition comprising an organic polyisocyanate composition (A), a polyol component (B), a catalyst (C), and a blowing agent (D),
The organic polyisocyanate composition (A) contains an isocyanate group-terminated prepolymer obtained from an isocyanate component containing diphenylmethane diisocyanate and dipropylene glycol,
The total content of 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate in the isocyanate component containing the diphenylmethane diisocyanate is 97% by mass or more, and the diphenylmethane diisocyanate is included. The total content of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate in diphenylmethane diisocyanate in the isocyanate component is less than 3% by mass, and the isocyanate group content of the organic polyisocyanate composition (A). is 15 to 25% by mass ,
The polyol component (B) contains polytetramethylene glycol (b1) having a number average molecular weight of 600 to 3,500,
A composition for integral skin foam, characterized in that the content of polytetramethylene glycol (b1) in the polyol component (B) is 80% by mass or more . An integral skin foam obtained from the integral skin foam composition according to claim 1 . 3. The integral skin foam according to claim 2, characterized in that the foam density is 200-400 kg/m ³ . 4. The integral skin according to claim 2 or 3 , having a rebound resilience modulus of 50% or more, a tear strength of 100 N/cm or more, and a split tear strength of 2.50 kg/cm or more. form. A method for producing an integral skin foam obtained by reacting and foaming an organic polyisocyanate composition (A) and a polyol component (B) in the presence of a catalyst (C) and a blowing agent (D). hand,
The organic polyisocyanate composition (A) contains an isocyanate group-terminated prepolymer obtained from an isocyanate component containing diphenylmethane diisocyanate and dipropylene glycol,
The total content of 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate in the isocyanate component containing the diphenylmethane diisocyanate is 97% by mass or more, and the diphenylmethane diisocyanate is included. The total content of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate in diphenylmethane diisocyanate in the isocyanate component is less than 3% by mass, and the isocyanate group content of the organic polyisocyanate composition (A). is 15 to 25% by mass ,
The polyol component (B) contains polytetramethylene glycol (b1) having a number average molecular weight of 600 to 3,500,
A method for producing an integral skin foam, characterized in that the content of polytetramethylene glycol (b1) in the polyol component (B) is 80% by mass or more .